When Charts Deceive Web Agents: A Paired Benchmark for Misleading Visualization-Grounded Tasks

Yisheng Li, Dongming Han, Hongkun Pan, Bingcheng Mao, Zijian Wang, Yunlong Mao, Wei Tong, Sheng Zhong


Abstract
Web agents increasingly browse, interpret, and act on web content on behalf of users. In many realistic workflows, however, the visual evidence they consume is not neutral: charts and dashboards can be misleading, shaping judgments without issuing any explicit malicious instruction. Unlike chart question answering, Web Agents treat charts as intermediate evidence whose misinterpretation can propagate into concrete downstream actions — a reliability risk that remains underexplored. We introduce MisVisAgentBench, the first paired executable benchmark for evaluating how misleading visualizations affect Web Agent execution. It comprises 280 task instances in matched clean–misleading pairs that differ only in chart evidence. We further provide a diagnostic framework that isolates misleading-induced failures from baseline task difficulty and captures execution-level effects such as extra browsing steps and decision hesitation. Across eleven vision-language Web Agents, replacing clean charts with misleading counterparts nearly halves the average task success rate, an absolute drop exceeding 34 percentage points. Moreover, these failures predominantly follow the targeted misleading action branch, suggesting that deceptive charts systematically redirect rather than randomly disrupt agent decisions. These results reveal that visualization robustness is a critical yet understudied dimension of Web Agent safety and reliability.
Anthology ID:
2026.findings-emnlp.1993
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
42466–42484
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URL:
https://aclanthology.org/2026.findings-emnlp.1993/
DOI:
Bibkey:
Cite (ACL):
Yisheng Li, Dongming Han, Hongkun Pan, Bingcheng Mao, Zijian Wang, Yunlong Mao, Wei Tong, and Sheng Zhong. 2026. When Charts Deceive Web Agents: A Paired Benchmark for Misleading Visualization-Grounded Tasks. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 42466–42484, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
When Charts Deceive Web Agents: A Paired Benchmark for Misleading Visualization-Grounded Tasks (Li et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.1993.pdf